Mechanical loading, or forces that stimulate cellular growth for development, is required for creating cartilage that is then turned to bone; however, little is known about cartilage development in the absence of gravity or mechanical loads. Now, in a study led by the University of Missouri, bioengineers have determined that microgravity may inhibit cartilage formation. Findings reveal that fracture healing for astronauts in space, as well as patients on bed rest here on Earth, could be compromised in the absence of mechanical loading.